1. The Study of Inherited Characteristics Ch 10.1 and Ch12
Genetics
The Study of Inherited Characteristics
Ch 10.1 and Ch12

2. Important Vocab.
Meiosis: a type of division that produces sex cells

3. Meiosis in the Gonads makes gametes:
Sperm
Meiotic cell
division
Egg

5. X Y

6. Gene
section of DNA on a chromosome that controls a specific trait.

7. Alleles RR Rr TT Tt Alleles are variations of a gene Code for a trait
One from each parent

8. Alleles Dominant Allele: Recessive Allele: R r
Upper case letter of the alphabet
Codes for dominant traits
Recessive Allele:
Lower case letter of the alphabet
Codes for recessive traits R r

9. Dominant Trait Bb BB or Bb “Dominates” Shows in the outward appearance
Even when recessive allele is present Bb BB or Bb

10. Bb Recessive Trait bb “hidden” May be masked by a dominant allele
Albinism
“hidden”
May be masked by a dominant allele Bb bb

11. Genotype Bb
Genotype: The allele combination of the organism (i.e. TT, Tt or tt)

12. Phenotype
Phenotype – the way an organism looks and behaves as a result of its genotype
(e.g. The rabbit looks brown (even though it might be Bb in its genotype)

13. Homozygous:
Pure condition
2 same case alleles
BB= dominant
bb= recessive
Heterozygous:
Hybrid condition
2 different case alleles Bb

14. How to Solve Genetics problems
READ and Make a Key
ex. B= black fur, b= white fur
Parent genotypes (Write them down) ex. BB x Bb
Gametes (Figure out what the gametes would be)
Fill in Punnett square to get offspring
Phenotypes/Genotypes of offspring (Write them out)– Best if written as a reduced fraction!

15. B BB Bb Monohybrid Cross Punnett Square Cross for one characteristic
Example:
Hair color

16. b B Generations Bb P generation = the original parents. Genetic Cross=
Mating
F1= Children
1st “filial” generation
Parents b B Bb

17. 2nd Generation- F2 B b BB Bb bb
Children of the cross between the children of an F1
The grandchildren of the original P generation parents B b BB Bb bb

18. Incomplete dominance Hybrid is a blend of traits Example:
RR=red
Rr=pink
rr=white
Pink Carnation

19. Codominance Codominance—showing both alleles at the same time
e.g. Checkered chicken (Black and white at same time)
B= Black
W= White
BB= Black,
WW =white
BW = black and white
(checkered).
Another example is Blood Type!
A, B, AB or O

20. Multiple Alleles More than two types of alleles for a gene. TYPES:
Example:
Blood Type
TYPES:
A IAIA, IAi
B IBIB , IBi
AB IAIB
O ii

21. Polygenic traits
Polygenic trait = a trait that is influenced by more than one gene.
e.g. Eye color, skin color, hair color, height, etc…
What do all of these characteristics have in common that can help you to recognize that the trait is polygenic?

22. X-Linked Traits Sex-linked Trait in on the sex chromosome XX= FemaleXY
Male
e.g. red & white eyes
Female= XX
Add eye trait=
XRXR or XRXr
XrXr
Male= XY
XRY or XrY
“Y” is empty

23. Color Vision

25. Mendel’s Laws Law of Segregation Law of Independent Assortment
when gametes are made, allele pairs segregate (separate) and randomly recombine at fertilization (with the allele of the other parent).
Law of Independent Assortment
genes for different traits (ex. Height and seed color) are inherited independently of each other.
(i.e. how tall you are will NOT affect what color your seeds are)

26. Chromosome Number Homologous Chromosomes are the sets of each pair
Different # for different species
Full set = 2N=Diploid N=
# pairs
1 pair from mother
1 pair from father
Humans= 23 pairs or
46 total

27. Autosomes & Sex Chromosomes
Autosomes = # 1-22 for all traits except sex
Sex chromosomes=
Pair # 23 XX(female) or
XY(male)

28. Trisomy: an additional chromosome e.g. Down Syndrome (3 of #21)

29. Klinefelter’s = XXY

30. Pedigree Charts
Male =
Female=
Sexual Union=
Offspring=

31. Pedigree Chart -Cystic Fibrosis

32. Mutation A to A G C A X T G C Change in DNA code Caused by:
Chemical damage
Errors in Replication
X-ray damage
UV damage A T
G C X

33. Mutation Changes in the DNA = Changes in the final proteins made
=Changes in the organism

34. Questions?